UltraScan™ CD Inspection Tool

UltraScan CD Inspection Tool

Reliability in Detecting Longitudinal Cracks

Pipeline failures due to stress corrosion cracking can be a problem for pipeline operators worldwide.The UltraScan™ CD tool was introduced in 1994 to locate cracks that run parallel to the axis of the pipe. In its first 1,000 km of field work in Europe, Russia and North America, it found more than 100 defects requiring a verification dig. All were accurately identified and verified by field excavation and measurement.

Features & Benefits

UltraScan™ CD locates and measures:

  • SCC
  • Fatigue cracks
  • Weld defects
  • Scratches
  • Grooves
  • Similar crack-like anomalies with a longitudinal orientation

You can rely on UltraScan™ CD to identify fine cracks as shallow as 1 mm, and it has accurately reported cracks half that depth. The tool’s record of reliability is such that an UltraScan™ CD inspection is accepted as an alternative to hydrostatic testing in many jurisdictions.

Analysis & Reporting

The data recorded by the UltraScan™ CD tool is processed by powerful software that identifies all significant features. The resulting database of potential anomalies becomes the foundation of the analytical process. For initial interpretation, the features are displayed as color C-Scans. Using custom tools and multiple B-Scan images, experienced engineers can identify and examine the minute flaws that comprise SCC colonies. The large number of sensors on the tool facilitate this process by taking multiple readings of each target, and distinguishing clearly between internal and external flaws.

UltraScan Images

The final report lists all crack-like flaws, with depth grading and location information. C-Scan images are provided for all documented features that meet the criteria set when the inspection was planned.

Operation

The UltraScan™ CD tool adapts a special application of ultrasound in non-destructive testing, the 45° shear-wave technique, to the special challenges of the in-line environment.

The pulses of ultrasound emitted by the tool are directed circumferentially into the pipewall at an angle that generates 45° shear-waves within the metal. The transducers are mounted on a flexible carriage at the rear of the tool. With large numbers of transducers generating pulses and receiving their reflections, as many as ten simultaneous readings can be taken from each flaw or pipeline feature. This high degree of redundancy compensates for any information loss that may occur, and increases the possibility of detecting all cracks of measurable size.

The sheer quantity of multiple-redundant readings presented two major issues during tool development. One was the need for an entirely new real-time data-processing algorithm. It is called ALOK, and is unique to our company. The other was the impossibility of storing such a large body of data within the moving tool. The solution is a higher level of pre-processing, which records only data groups associated with crack-like defects. Even so, in a typical 100 km run, a 24 inch tool can gather as much as 24 gigabytes of data.

Because the metal adjacent to the longitudinal seam is a prime development site for SCC, data gathered from this area is recorded unfiltered to deliver maximum information. A separate set of sensors records wall thickness and identifies girth welds, useful as reference points. Tool position is also tracked by means of odometer wheels and above-ground markers. As with the UltraScan WM, UltraScan™ CD must be coupled to the work-piece by a liquid medium. In dry pipelines, it can be run in a liquid batch.

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